VME, Motorola MVME162?

[Staffan321]

Hello,

I'm looking for help with the Motorola MVME162 CPU board. It has a battery backed RAM (BBRAM), which is about to die on my machine and unless I get to understand how to save its data before it's too late, the current application will refuse to boot.

Is this the right forum for these questions or can anyone please recommend other places to look?

Many thanks in advance!

Regards,
  Staffan

[Ampera]

if it has an exposed battery, one solution is to find two points on the part of the board responsible for your RAM refresh circuitry, and attack a power supply equal to that of the battery to it. Ensure it is secure, then replace the battery, and then disconnect the power supply. Ensure you don't hang around like this for too long, as most batteries don't like power being shoved into them willy nilly (though NiCd tech is usually alright).

If it is not, then you should look towards software solutions for dumping the RAM, or if you can program something like a TL886 to read the RAM chip (presuming this RAM chip has an internal battery like a Dallas RTC), that may be another solution.

[ebastler]

Google suggestst that the non-volatile RAM is a MK48T08, which seems to have the standard pinout for an 8kb*8 RAM or ROM.

Is it socketed? In which case you could start by reading it out with an EEPROM programmer (or a little custom program for whichever microcontroller development board you may have on the shelf.)

There are various DIY instructions floating around on the internet which desribe how to hack a fresh battery into the similar DALLAS clock/SRAM chips. Haven't seen one tailored to the STM MK48T08, but I assume it's out there somewhere...

On the other hand, STM's catalog suggests that the MK48T08 is still an active part, so you should be able to just buy a new one -- then again program it via an EEPROM programmer or a microcontroller:  https://www.st.com/en/clocks-and-timers/rtc-parallel-interface-timekeepers.html#products

[Staffan321]

Hello,

Many thanks for the suggestions! The M48T08 is soldered firmly on to the board as it seems. I’m hoping to get some suggestions on how to access the data before playing around too much. Hopefully, there is some standard rom that could be inserted instead of my current one. Just don’t know where to look. The board seems to be very standard - MVME162.

Regards,
 Staffan

[ebastler]

Hi Staffan, if the MK48T08 chip is soldered in, it's probably easiest to write a little program for the MVME162 board itself to read out that RAM? Then you would have a backup, and can start to figure out how you want to proceed further: Hack the MK chip open to install a fresh battery, unsolder it to install a new one, or whatever.

A memory map of the system is available, so you know where to find the MK48T08:
https://www.naic.edu/~phil/hardware/motorolasbc/mvme162EmbeddedCtrlInstallationGuide.pdf

[Staffan321]

Hi,

I would love to write a program, but lack absolutely everything for VME... I can program an eprom if I had the binary, but that’s all. Any hint on how to proceed would be great!

Is there an ide available perhaps? Best would be if there were binaries I could program and put into the board so that it would run a debugger that I could play with.

Regards,
 Staffan

[fourtytwo42]

I am thinking about this, I used to work a lot with various Motorola (& other) VME products, so this board is part of a system, what is it ?
It may be that someone from the product developer may be able to help you. Most product developers left the basic board "BIOS" intact so if you attach yourself a terminal (or emulator) to a serial port 9660bps bit you might get a prompt.

You sound like this thing has never (in recent history) been power cycled, is that true, is it on a UPS or something ?

[Staffan321]

Hello,

The VME board (MVME162 from Motorola very similar to this one: https://upload.wikimedia.org/wikipedia/commons/e/e6/Motorola_MVME162-023.jpg) sits as the CPU in a network analyzer (RF/microwave) from Anritsu/Wiltron. It's a 37247, 0-20 GHz analyzer that I have had the fortune to get hold of. It has probably been running continuously for years judging by the reported ON time, but the last years it has just been sitting since it was broken (in power OFF, wearing out the BBRAM battery).
So far I have spent quite some time on fixing the RF hardware (my area), but now realize I have a problem with the digital hardware (not my area...).
There are many connectors on the CPU board itself, but none that is an obvious serial port. It would be brilliant if I could get into the board by just connecting to one of these connectors with a serial terminal! I have a VME extension board so I should be able to reach any connector even when it's hooked up. It's urgent that I get this done though because I read on other threads that these analyzers get bricked if the BBRAM dies and I sincerely don't want that!

From what I understand, there is unlikely any help to get from the manufacturer and I have seen no one showing how to connect this type of analyzer to a serial port. Still, as you mention, it doesn't sound too unlikely that the developers would leave a debug port on the board unless it had to be removed for space (maybe, maybe not).

Any help on getting hold of the BBRAM content would be very much appreciated!

Regards,
   Staffan

[dexters_lab]

This should be a simple job once the IC is removed from the board which you'll need to do anyway to drop in a new one, the M48T08 is still a current product so you can just buy a new one rather than hacking a new battery onto the old one. If you solder in a socket at the same time it'll make future replacement easy.

Once the device is removed you can wire up an adaptor board and read the contents in an EPROM reader like TL866.

The address and data lines match the TMS2764 EPROM but for programming you'll need to isolate pin 1 of the 48T08 from the TL866 so it doesn't try to feed 21 volts into the 48T08's INT pin when it writes.

I've done this so many times to read NVRAMs and PROMs i made a re-wireable adaptor:

[fourtytwo42]

I agree with Dexter BUT it's gonna be a hell of a task to desolder it as the pins are not exposed on the top of the pcb like a normal DIP, just remember to rest between wicking pins so as not to overheat the battery...........

This https://www-mipp.fnal.gov/TPC/DAQ/162_d2.pdf does however say there are two RS232 serial ports AND I quote "MVME162Bug  occupies  the  first  half  (512KB)  of  Flashmemory" so if you read the manual you might find out how to access it and hence the M48T08 contents (this being an insurance policy against loss of contents or a pin whilst desoldering).

[helius]

Another thing to keep in mind is that the contents of the NVRAM may be upset by the desoldering process, depending on the specifics of the battery circuit and voltages present on the pins.

[Staffan321]

Hello,

Just a short update. After a closer inspection, it turned out that the NVRAM was in fact not soldered to the board. I just lifted it up, read out data using a TL866 and yes, after insulating pin 1, it was quite straightforward to program a fresh IC (not from ebay this time)!

Many thanks for all input!

Regards,
  Staffan